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D J Thompson - One of the best experts on this subject based on the ideXlab platform.
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a framework to predict the airborne Noise inside railway vehicles with application to Rolling Noise
Applied Acoustics, 2021Co-Authors: D J Thompson, Pascal Bouvet, Giacomo Squicciarini, Xiaowan Liu, Martin Rissmann, F D Denia, Luis Baeza, Julian Martin Jarillo, Juan Moreno GarcialoygorriAbstract:Abstract A framework is described for predicting the airborne Noise inside railway vehicles which is applied to Rolling Noise sources. Statistical energy analysis (SEA) is used to predict the interior Noise by subdividing the train cabin into several subsystems. The dissipation loss factors are obtained from the measured reverberation time in the train cabin. The power input to the interior SEA model is obtained from the external Noise sources by multiplying the incident sound power on the external surfaces with measured transmission coefficients of the train floor and sidewalls. The sound power incident on the train floor is calculated by using an equivalent source model for the wheels and track together with an SEA model of the region below the floor. The incident sound power on the sides is obtained by using a waveguide boundary element (2.5D BE) method. The procedure is applied to a Spanish metro train vehicle running in the open field for which Rolling Noise is the main external Noise source. The procedure is verified by field measurements of sound pressure beneath the carriage, on the sidewalls and inside the vehicle. The sensitivity of the results to changes in interior absorption is also studied, including the effect of passengers.
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a comparison of Rolling Noise from different tram tracks
2021Co-Authors: Wenjing Sun, D J Thompson, Martin Toward, Marcus Wiseman, Evangelos NtotsiosAbstract:A number of different track forms are studied from one tramway system including tracks in ballast, on slab, and embedded rail in grass. Measurements have been carried out of rail roughness, wheel roughness and track decay rate, which are used as input data for the Noise prediction model TWINS. The rail vibration and exterior Noise of trams in operation have also been measured for comparison with the prediction model. The model is used to identify the relative contributions of Noise radiated by the track and the wheels. The differences between different track forms are determined and the reasons for them are identified.
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modelling wheel rail Rolling Noise for a high speed train running on a slab track
2021Co-Authors: Xiaozhen Sheng, Gong Cheng, D J ThompsonAbstract:About 35,000 km of high-speed railways are in operation in China with a maximum operational speed of 350 km/h. The main track form on the high-speed lines is non-ballasted slab track. Measured data show that at high speeds, Rolling Noise is still a dominant source for both interior and exterior Noise. Although Rolling Noise modelling has been conducted for more than 30 years, a train running at 350 km/h or higher along a non-ballasted slab track brings many new factors which have not been adequately addressed in the past. The aim of this paper is to describe a new approach that brings together elements that have been developed by the authors to model Rolling Noise from a high-speed train running on a slab track, and to present some results for a typical high-speed train and track, including Rolling Noise frequency spectrum, dependence on train speed, and contributions of the wheel, rail and slab.
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modelling wheel rail Rolling Noise for a high speed train running along an infinitely long periodic slab track
Journal of the Acoustical Society of America, 2020Co-Authors: Xiaozhen Sheng, Gong Cheng, D J ThompsonAbstract:Around 35 000 km high-speed railways are in operation in China with a maximum speed of 350 km/h. The main track form on the high-speed lines is non-ballasted slab track. Measurements show that, at high speeds, Rolling Noise is still the dominant source for both interior and exterior Noise. Although Rolling Noise modelling has been investigated for more than 30 years, a train running at 350 km/h or higher along a non-ballasted slab track introduces a number of new factors which have not been adequately addressed in the past. The aim of this paper is to describe an approach that brings together elements that have been developed recently to model Rolling Noise for a high-speed train running on a slab track. Features of the approach include modelling interactions between multiple moving and rotating wheelsets with an infinitely long periodic track, treating all the radiators as moving sources, and directly predicting sound pressure frequency spectra for observation points near the track. Results are produced for a typical Chinese high-speed train and track, including wheel and rail receptances, wheel/rail forces, comparison of Rolling Noise with measured pass-by Noise, dependence on train speed, and contributions from the wheelset, rail, and slab.
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influence of rail fastener stiffness on railway vehicle interior Noise
Applied Acoustics, 2019Co-Authors: D J ThompsonAbstract:Abstract More attention has been paid in recent years to the interior Noise of railway vehicles. It has been observed that the interior Noise can increase in some locations where vibration-isolation measures are used in the track structures. In order to assess the influence of vibration isolation measures on the Noise levels inside railway vehicles, a field measurement campaign has been carried out. The vehicle interior Noise has been measured when a train is running at different speeds over the same non-ballasted track section fitted with two types of rail fastener of different stiffnesses. Additional measurements of axlebox vibration, train floor vibration, exterior Noise and rail vibration are used to investigate the influence of the fasteners further. The experimental results are compared with simulations performed using the TWINS model, considering the wheel/rail interaction, by focusing only on the relative differences between the two fastener systems. The axlebox vibration and rail vibration are predicted for a unit roughness input and the differences in Rolling Noise are also obtained. The predicted differences in axlebox vibration, rail vibration and Rolling Noise are in broad agreement with the measurement results. The results show that the fasteners with a lower stiffness cause a noisier interior environment. Around 125 Hz and in the frequency range 315–1000 Hz, the Noise levels are higher for the more elastic fastener, with an average level difference of 3 dB in the latter frequency range. It appears from the shape of the level difference spectra that airborne Noise has most influence between 100 and 400 Hz and structure-borne Noise has more influence between 500 and 1000 Hz.
C.j.c. Jones - One of the best experts on this subject based on the ideXlab platform.
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railway Rolling Noise prediction field validation and sensitivity analysis
International Journal of Rail Transportation, 2013Co-Authors: Shijie Jiang, D J Thompson, Paul A Meehan, C.j.c. JonesAbstract:The Railway Rolling Noise Prediction Software (RRNPS) is a model for predicting the sound pressure levels (SPLs) during a train passage due to wheel/rail roughness, based on vibration dynamics, contact mechanics and sound radiation modules. Similar software has been developed previously, in particular the Track–Wheel Interaction Noise Software (TWINS) model, and some field validation has been done under European and Japanese conditions. In this article, the RRPNS is used to model a typical railway Rolling Noise situation in Australia and compared with detailed field experimental results for validation purposes. A series of field measurements were taken at a narrow track gauge testing site in Australia. Comparisons between simulations and measurements have shown that this software model gives reliable predictions in terms of overall A-weighted SPL and Noise spectrum. In addition, a sensitivity analysis of the model was carried out to investigate the effect of speed, normal load, ballast vertical stiffness,...
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Noise and vibration from the wheel rail interface
Wheel–Rail Interface Handbook, 2009Co-Authors: D J Thompson, C.j.c. JonesAbstract:Abstract: This chapter discusses the various types of Noise arising from the wheel–rail interface and means for contRolling them. The main source is Rolling Noise which occurs on plain track and has a broad frequency content. Discrete features such as rail joints and wheel flats generate impact Noise, whilst in curves very high squeal Noise levels can be produced. In each of these cases, the Noise has its origins at the wheel–rail interface, but it is not emitted from the interface region itself. In the case of both Rolling and impact Noise, vibration of the whole wheel structure and of a considerable length of track are involved in radiating the Noise. For curve squeal, specific modes of vibration of the wheel radiate the Noise. At low frequencies, vibration is transmitted through the ground and may be experienced either as feelable vibration or as a low frequency rumbling Noise.
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the use of decay rates to analyse the performance of railway track in Rolling Noise generation
Journal of Sound and Vibration, 2006Co-Authors: C.j.c. Jones, D J Thompson, R J DiehlAbstract:Through the development and testing of theoretical models for Rolling Noise in the past, it has been well demonstrated that the rate of decay of vibration along the rail is closely linked to the Noise performance of the track, since it controls the effective radiating length of the rail. The decay rates of vibration along the rail have long been used by researchers as an intermediate, measurable parameter by which to test and improve the accuracy of prediction models. Recently, it has been suggested that the decay rates should be used as a criterion for the selection of track for Noise measurements that are part of the acceptance testing of interoperable trains in Europe. In this context, a more detailed understanding of the factors that affect the measurement of decay rates and a consistent approach to the data processing have become important topics. Here, a method is suggested for the calculation of decay rates from frequency response measurements. Different effects are shown in the measured decay rates of a ballasted track with mono-bloc sleepers, a slab track and a ballasted track with bi-bloc sleepers. In the last case, a model for a periodically supported track is used to study the effects observed. It is shown that a peak in the decay rate just above the pinned–pinned frequency may be overestimated because of the measurement procedure that has been used.
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railway Noise measurement method for pass by Noise total effective roughness transfer functions and track spatial decay
Journal of Sound and Vibration, 2006Co-Authors: M H A Janssens, M. G. Dittrich, F G De Bee, C.j.c. JonesAbstract:In recent years, considerable effort has been spent at a European level to establish comprehensive methods for the experimental assessment of Rolling Noise emission of rail-bound vehicles and tracks. This work was concentrated in the European METARAIL and STAIRRS projects. The objective of these was to improve the accuracy and the reproducibility of pass-by Noise measurements compared to the standards that were current at that time. A further aim was to develop experimental methods separately to identify the contributions to Rolling Noise of the vehicles and the tracks. In these projects, measurement methods were developed that could determine the combined wheel/rail roughness and the 'transfer functions' for the vehicle and the track, that is, the separate Noise contributions per unit roughness. The roughness and transfer function spectra provide a powerful basis by which vehicles and tracks can be characterized by measurement, to a high extent, independent of the running speed and site conditions. Such a description of the track and Rolling stock allows the prediction of Rolling Noise spectra for different combinations of vehicles and track from those at which the characteristics have been measured. The measurement effort is limited; only straightforward one-third octave band measurements of pass-by sound pressure and vertical railhead vibration are needed. This paper describes the method, giving the derivation of the calculation by which the roughness levels, transfer function spectra levels and the vibration decay rates in the track are determined from the measured quantities. Typical results are shown. Among other applications, the method allows fast assessment of wheel roughness for whole vehicles or trains, speed-independent assessment of the effectiveness of track and vehicle Noise control measures and the separation of Rolling Noise from Noise due to other sources.
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extended validation of a theoretical model for railway Rolling Noise using novel wheel and track designs
Journal of Sound and Vibration, 2003Co-Authors: C.j.c. Jones, D J ThompsonAbstract:A theoretical model for railway Rolling Noise, TWINS, was first developed some years ago and was previously validated against field measurements for conventional wheel and track designs. This model has subsequently been used in the design of Noise-reducing wheels and tracks. An outcome of the recent Silent Freight and Silent Track projects was a series of novel designs that were tested in a comprehensive field experiment. Alongside this development, the theoretical model has been updated to improve accuracy and include new features. The results of 34 wheel/track combinations that were measured in field experiments are compared with corresponding predictions using the improved model. It is found that the mean difference between measured and predicted overall A-weighted sound pressure levels is less than 2 dB while the standard deviation is 1.9 dB. The improved accuracy of the model is also shown by a reanalysis of the original validation experiments.
Fabienne Anfossoledee - One of the best experts on this subject based on the ideXlab platform.
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statistical estimation of low frequency tyre road Noise from numerical contact forces
Applied Acoustics, 2013Co-Authors: G Dubois, Fabienne Anfossoledee, H P Yin, Julien Cesbron, Denis DuhamelAbstract:This paper deals with the relation between tyre/road numerical contact data and close-proximity (CPX) Rolling Noise measurements. The Noise was measured on several road surfaces together with the road texture in three dimensions on two-metre-long sections. A multi-asperity contact model was used to calculate successively the contact forces distribution and the contact pressure distribution between a tyre (slick or patterned) and the road during Rolling. The correlation between third-octave contact force levels and Noise levels was studied on a set of road surfaces with various textures. A high positive correlation was found at low frequency, which allows the estimation of Noise levels by means of statistical relations for each third-octave band between 315 Hz and 1000 Hz for the slick tyre and between 315 Hz and 800 Hz for the patterned tyre. The results of the model are discussed in relation to the standard deviation of CPX measurements.
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geometric descriptors of road surface texture in relation to tire road Noise
Transportation Research Record, 2002Co-Authors: Fabienne AnfossoledeeAbstract:The paper deals with the determination of geometric parameters for studying the relationship between tire-road Noise and texture of road surfaces. The approach was found to be an alternative to classical spectral analyses and numerical simulations of the tire-road contact. Texture parameters were derived from previous works at the Laboratoire Central des Fonts et Chaussees related to the influence of the microtexture of road surfaces on skid resistance. Use of these parameters was justified by consideration of generation mechanisms of Rolling Noise. Texture, Rolling Noise, and absorption measurements were performed on 12 road surfaces. The measuring devices and the test methods produced texture profile analyses, including the spectral and geometric approaches. Geometric parameters were defined. Correlation between the Noise and texture spectra showed results similar to those published in previous works. Fair tendencies were found between the global Noise level at 90 km/h and the geometric parameters. Unex...
Sangkeun Ahn - One of the best experts on this subject based on the ideXlab platform.
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Complex structured polymer concrete sleeper for Rolling Noise reduction of high-speed train system
Composite Structures, 2019Co-Authors: Sangkeun Ahn, Semin Kwon, Yeon-taek Hwang, Hyo-in Koh, Hak-sung Kim, Junhong ParkAbstract:Abstract Damping performance of complex polymer concrete sleeper for high-speed trains was identified after considering the radiation characteristics of Rolling Noise. Actual size complex concrete sleepers were fabricated to compare the damping characteristics. The wave type polymer concrete structure was embedded into the cement concrete sleeper. The measured dynamic properties of the complex concrete sleeper were compared with those of the cement concrete sleeper. The effects on improved damping performance due to the periodic polymer structure were investigated. The averaged dynamic properties of the sleepers were used to prediction of the Rolling Noise generation. A running train on the rail track was assumed as the moving load on the infinite Timoshenko beam. The relationship between the loss factor of the supporting stiffness and the rail vibration was analyzed. The radiated sound pressure from the rail vibration was predicted for the running train. Using complexed structured concrete sleeper, the radiation of the Rolling Noise was reduced effectively. This investigation on the concrete sleeper embedded with wave-type polymer concrete contributes to the study of complex railway structures to secure quite residential space with minimal influence from running trains.
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???????????????, 2018Co-Authors: Sangkeun AhnAbstract:Train system is essential transportation due to its high speed and large scale comparing with vehicle. Although train system has many benefit as above, radiated sound from train make annoyance to residents near railroad. The train Noise mainly consists of aerodynamic Noise, driving Noise from power sources, Rolling Noise from wheel, rail track and sleepers. When train running faster than 300 km/h, the aerodynamic Noise becomes dominant component of the train Noise. However, Rolling Noise contributes train Noise over all speed range. To reduce Rolling Noise, the web damper installed on the track and the high damping pad under the track have been investigated. The web damper covers only low frequency range and rail pad causes high maintenance cost. Cement concrete sleeper of high speed railway is major component of the rail system. Due to flexural deflection of train and rail track, elastic characteristics of concrete sleeper affects vibration of rail system. High damping concrete sleepers are needed to solve the Noise problem induced from Rolling Noise. Radiation characteristics of Rolling Noise was predicted by applying moving load theorem. Running train on rail track is modeled as moving load on infinite beam. Relationship between the loss factor of supporting stiffness and the rail vibration was analyzed. Radiated sound power and directivity of Rolling Noise from rail vibration were identified with different the load velocity. Concrete cement has been widely used as a material in civil engineering structures due to its flexibility and load holding capabilities. However, Portland cement concretes have exhibited problems arising from excessive Noise and vibration generation due to their low damping. In this paper, polymer concretes made with an epoxy resin were studied and their ability to reduce Noise/vibration in a concrete slab track was examined. The polymer concretes were fabricated with different mixing ratios of the epoxy resin/aggregate and aggregates of different sizes. The effects of these variables on the compressive and flexural strengths of the polymer concretes were measured to study the mechanical reliability under water absorption environments. Also, the frequency dependent variations of stiffness and damping in the polymer concretes were obtained by impact vibration tests to study their ability to reduce vibrations. The fatigue tests of the concretes were performed by applying periodic load for bending tests. To investigate the reduction of stiffness due to fatigue damage, the frequency dependent variations of the dynamic stiffness and the loss factor of the polymer concretes (a mixture of epoxy resin, carbon fiber and aggregates) were obtained by impact tests. The variation of the dynamic properties before and after the fatigue tests was measured. The separated beam method was used to identify the stiffness distribution along the concrete specimen. This method analyzed the beam vibration using evenly spaced beam elements. The boundary conditions of displacement and slope continuity at end of each element were imposed. The least square method was applied to estimate the dynamic properties of the beam elements from the measured vibration response. This procedure was required to identify small change in the dynamic properties induced during fatigue tests. Consequently, the durability of the carbon fiber reinforced polymer concretes was validated by comparison with normal polymer concretes. A pipe structure was embedded in polymer concrete specimens. The frequency-dependent variations of the dynamic stiffness and the loss factors of the specimens were measured by the vibration test method so that the damping enhancement from the embedded structure could be identified. The weight reduction effect of epoxy resin usage was compared after pipe embedment. Impact dampers were applied to the pipe-embedded polymer concretes to improve their vibrational energy dissipation. The impact dampers were fabricated through the insertion of impact balls into the pipe structures. The dynamic properties of the impact-damper-positioned polymer concretes were obtained by vibration tests. The damping performance was investigated according to the gap size between the impact ball and the pipe. An analytic model was used to predict the vibrational behavior of the polymer concrete when the impact dampers were applied. Consequently, the effect on vibration damping was identified for different mass ratios and gaps to find optimal construction. As another way to improve damping performance of the concrete sleeper, complex concrete which is polymer concrete was inserted in cement concrete was fabricated. The adhesion force at the interface between the polymer concrete and the cement concrete was investigated from impact test. A cylindrical embedment structure was fabricated by using a silicon mold and the embedment was placed in direction of length and height. From the cylindrical embedment, more suitable embedment shape was determined by measuring the flexural strength and the loss factor. A wave type embedment structure was designed in order to improve the performance of the complex concrete. With the longitudinal direction, the height of the polymer concrete change continuously. The responses of the complex concretes were also measured using accelerometers by impact excitation. The characteristics of the metamaterial was identified from the periodic nonlinear interface. An analysis model considering the classical laminate theorem to investigate the damping effect of wave type embedment was imposed. To verify the damping performance of meta-structured concrete, actual size meta-structured concrete sleeper was fabricated. The averaged loss factor of the complex sleeper in frequency range from 50 Hz to 3.2 kHz was compared with that of the cement concrete sleeper. It was found that the meta structure using the polymer concrete wave pattern is also effective in improving damping performance of an actual concrete sleeper. Lastly, the dynamic properties of the measured complex concrete were applied to the Rolling Noise analysis model. The Rolling Noise form railway in velocity of 300 km/h was analyzed. Using meta-structured concrete sleeper, the radiation of the Rolling Noise was reduced effectively. This investigation on the characteristics of concrete sleeper embedding wave type polymer concrete contributes to study of complex slab railway structures to minimize the vibration and Noise generation from running trains.Docto
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investigation of damping in the polymer concrete sleeper for use in reduction of Rolling Noise from railway
Journal of the Acoustical Society of America, 2014Co-Authors: Sangkeun Ahn, Hak-sung Kim, Junhong Park, Eunbeom Jeon, Hyoin KhoAbstract:The purpose of this study was to measure damping of various polymer concretes to be used as sleepers for railway. The polymer concretes consisted of epoxy monomer, hardener and aggregates. Various polymer concrete specimens were made by changing epoxy resin weight ratio and curing temperature. The dynamic properties of the polymer concrete specimens were measured by using beam-transfer function method. To predict reduction performance of the polymer concrete sleepers, an infinite Timoshenko beam model was investigated after applying measured concrete properties. The moving loads from rotating wheels on railway due to different roughness were utilized in railway vibration analysis. The vibration response was predicted from which the effects of supporting stiffness and loss factor of sleeper were investigated. The radiated sound power was predicted using calculated rail vibration response. Consequently, the sound power levels were compared for rails supported by different polymer concrete sleepers. The result of this study assists constructing low Noise railway.
Junhong Park - One of the best experts on this subject based on the ideXlab platform.
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Complex structured polymer concrete sleeper for Rolling Noise reduction of high-speed train system
Composite Structures, 2019Co-Authors: Sangkeun Ahn, Semin Kwon, Yeon-taek Hwang, Hyo-in Koh, Hak-sung Kim, Junhong ParkAbstract:Abstract Damping performance of complex polymer concrete sleeper for high-speed trains was identified after considering the radiation characteristics of Rolling Noise. Actual size complex concrete sleepers were fabricated to compare the damping characteristics. The wave type polymer concrete structure was embedded into the cement concrete sleeper. The measured dynamic properties of the complex concrete sleeper were compared with those of the cement concrete sleeper. The effects on improved damping performance due to the periodic polymer structure were investigated. The averaged dynamic properties of the sleepers were used to prediction of the Rolling Noise generation. A running train on the rail track was assumed as the moving load on the infinite Timoshenko beam. The relationship between the loss factor of the supporting stiffness and the rail vibration was analyzed. The radiated sound pressure from the rail vibration was predicted for the running train. Using complexed structured concrete sleeper, the radiation of the Rolling Noise was reduced effectively. This investigation on the concrete sleeper embedded with wave-type polymer concrete contributes to the study of complex railway structures to secure quite residential space with minimal influence from running trains.
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investigation of damping in the polymer concrete sleeper for use in reduction of Rolling Noise from railway
Journal of the Acoustical Society of America, 2014Co-Authors: Sangkeun Ahn, Hak-sung Kim, Junhong Park, Eunbeom Jeon, Hyoin KhoAbstract:The purpose of this study was to measure damping of various polymer concretes to be used as sleepers for railway. The polymer concretes consisted of epoxy monomer, hardener and aggregates. Various polymer concrete specimens were made by changing epoxy resin weight ratio and curing temperature. The dynamic properties of the polymer concrete specimens were measured by using beam-transfer function method. To predict reduction performance of the polymer concrete sleepers, an infinite Timoshenko beam model was investigated after applying measured concrete properties. The moving loads from rotating wheels on railway due to different roughness were utilized in railway vibration analysis. The vibration response was predicted from which the effects of supporting stiffness and loss factor of sleeper were investigated. The radiated sound power was predicted using calculated rail vibration response. Consequently, the sound power levels were compared for rails supported by different polymer concrete sleepers. The result of this study assists constructing low Noise railway.
